Apparatus and method for separating flat articles

ABSTRACT

In an apparatus for separating flat articles of a stack, operating elements of one side of a transport path are fastened on a sliding plate which, in the individual-separation state, is moved away from the transport path and back again and is driven in a controlled manner. In the event of a fault warning from a sensor set-up for determining fault states during the individual-separation process, transport elements moving the articles along the transport path are stopped, and the sliding plate is moved into an individual-separation position for opening the transport path and, after a short time, for re-closing the transport path. After closing of the transport path, the transport elements resume their transport operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to German application no. 10 2007 007813.9, filed Feb. 16, 2007, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The invention relates to an apparatus and a method for separating flat articles. Such an apparatus and such a method are known from DE 10350623 B3. At the start of the process chain of a consignment-processing machine is located an individual-separation apparatus in which the consignments of a consignment stack are individually separated and transferred to a following transport zone. In the individual-separation apparatus, high forces act on the consignments, with the result that most transport faults arise there.

For fault elimination, it is known to eliminate the transport fault by the operator by the jammed consignments being drawn out of the closed transport path of the individual-separation apparatus. Extraction is complicated and time-consuming because the forces of the transport elements still act on the consignments. The consequence is mostly a further destruction of the consignments. Further, it is known to manually open the transport path by the operator and extract the consignments involved in the transport fault from the opened transport path. The transport path is subsequently closed manually by the operator.

Both solution variants are highly time-consuming and markedly reduce the machine throughput. The operator is additionally burdened by the handling work described.

SUMMARY OF THE INVENTION

The object on which the invention is based is to provide an apparatus for separating flat consignments, and a method, in which only little effort is required for fault elimination.

Accordingly, one aspect involves an apparatus for separating flat articles of a stack of articles when operated in an individual-separation mode. The apparatus includes a plurality of transport elements for transporting the articles, a drive for moving the transport elements, and at least one retention element for retaining the articles, wherein the transport elements and the retention element are configured to transport the articles in the individual-separation mode on a transport path through between the transport elements to individually separate the articles. The apparatus includes further a mounting, a mounting drive for moving the mounting, and a control unit for controlling the drive for moving transport elements and the mounting drive. At least one of the transport elements and the retention element is fastened to the mounting, wherein the mounting is configured to cause a movement of the mounting to vary a distance between the transport elements and the retention element. The control unit interrupts the individual-separation mode and stops the transport element drive after the reception of a fault signal, and subsequently activates the mounting drive to move the mounting to increase a distance between the transport elements and the retention element. Further, the control unit activates the mounting drive to move the mounting to reduce the distance between the transport elements and the retention element, and shifts the apparatus into the individual-separation mode and starts the transport element drive.

In a large proportion of transport faults, consignments are not correctly oriented in the transport path, with the result that they are not transported properly and therefore obscure monitoring sensors for an unduly long time, without their being a serious consignment build-up. So as not to trigger unnecessary action by the operator in these cases, the transport path is briefly opened automatically, with the result that the incorrect position of the consignments is corrected automatically by falling down. An automatic restarting of the individual-separation apparatus subsequently takes place. The machine stoppage and therefore the throughput loss are considerably reduced as a result.

In order to assist the automatic orientation of the consignments when the transport path is opened and to loosen any possible slight snaggings, transport elements can briefly be driven in the transport direction and/or opposite to the transport direction and then stopped again.

Furthermore, it is advantageous, for the cost-effective implementation of the sensor set-up for determining fault states, to arrange a row of light barriers along the transport path, in which case, when a defined obscuring time of elements of the row of light barriers is overshot as a result of improperly transported consignments, a fault is signaled until the obscuring of the elements of the row of light barriers is canceled.

Should the fault not yet be eliminated by means of the measures described, then it is advantageous, after the automatic opening and closing of the transport path and resumption of individual-separation operation, to open the transport path again by means of the drive of the sliding plate, to stop the transport elements and to resume individual-separation operation automatically only after the triggering of a manual signal after manual fault elimination simply by the extraction of the respective, then unjammed consignments.

In a low-effort version, the retention elements and further operating elements are arranged on the movable sliding plate for opening the transport path.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The novel features and method steps characteristic of the invention are set out in the claims below. The invention itself, however, as well as other features and advantages thereof, are best understood by reference to the detailed description, which follows, when read in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a diagrammatic top view of an individual-separation apparatus with a closed transport path, and

FIG. 2 shows a diagrammatic top view of an individual-separation apparatus with an opened transport path.

DETAILED DESCRIPTION OF THE DRAWINGS

In the exemplary embodiment, the articles to be individually separated are mail consignments. Before individual separation, these articles form a stack and are aligned with the consignment lower edges. The consignment stack located in the infeed region 12 stands on underfloor belts 13, is aligned, furthermore, at the end-face front edges by means of a supporting and guide element 14 and is held by stack supports, not illustrated.

The underfloor belts 13 and the stack supports convey the consignment stack in the direction of draw-off rockers pivotable about deflection rollers, located at the rear in the transport direction, of the draw-off belts 15, until said draw-off rockers have reached their working position. After the working position of the draw-off rockers has been reached, all the drives to the transport path are then started. These are the power take-offs of the draw-off belts 15 of the draw-off rockers, of following further transport belts 11 and of a transfer device with a press-down rocker 5 along the transport path. The foremost consignment 10 of the consignment stack is drawn off from the stack by the draw-off belts 15 and is then transported through the transport path by the transport belts 11. At the end of the transport path, the transfer of the consignments to a following processing stage then takes place by means of the transfer device.

As may be gathered further from FIG. 1, a retention band 2 is located on the transport path on the stack side, opposite to the draw-off and transport belts 15, 11 and the driven roller of the transfer device, on a sliding plate 7 mounted movably perpendicularly to the transport direction by means of linear guides 6. The retention band presses by means of sprung press-down elements 1 against the transported consignments 10 which are thereby, in turn, pressed onto the driving transport elements 15, 11.

Furthermore, a guide fence 3 and one half of a row of light barriers 4, running along the transport path, of a sensor set-up for determining the fault states during the individual-separation process are arranged on the sliding plate 7. By means of the row of light barriers 4, the position of the consignments in the transport path at any time point is determined. The sliding plate 7 is moved by an eccentric 8 driven motively or pneumatically, with the result that the transport path is opened or closed. The end positions of the sliding plate 7 are located at the respective dead centers of the eccentric 8.

When a transport fault is detected owing to too long an obscuring of the light barriers 4, the transport elements 11, 15 are stopped. The eccentric 8 executes half a revolution to its next dead center and moves the sliding plate 7 away from the closed transport path (FIG. 2). All the elements 1 to 6, 8 on the sliding plate 7 are thereby also moved back, and the consignments 10 are freed automatically of any press-down.

Owing to the optional brief activation of the drive to the transport belts 11 (in the transport direction and/or opposite to the transport direction of the consignments), consignments or consignments parts which are introduced too high fall more reliably down into the transport path. The automatic restarting of all the transport elements 11, 15 with the automatic closing of the transport path as a result of the movement of the sliding plate 7 by means of the eccentric 8 makes time-consuming intervention by the operator unnecessary.

If, nevertheless, the consignment build-up cannot be eliminated automatically in this way, the transport elements 11, 15 are stopped once more and the transport path is opened. The consignments causing the build-up can thereafter be extracted manually without any pressure on the consignments. The automatic sequence is subsequently restarted, specifically by manually triggering a fault elimination signal. As a person skilled in the art can easily recognize, it is also possible to arrange the transport elements (draw-off and transport belts 15, 11) on a movable sliding plate 7. 

1. An apparatus for separating flat articles of a stack of articles when operated in an individual-separation mode, comprising: a plurality of transport elements for transporting the articles; a drive for moving the transport elements; at least one retention element for retaining the articles, wherein the transport elements and the retention element are configured to transport the articles in the individual-separation mode on a transport path through between the transport elements to individually separate the articles; a mounting, wherein at least one of the transport elements and the retention element is fastened to the mounting, and wherein the mounting is configured to cause a movement of the mounting to vary a distance between the transport elements and the retention element; a mounting drive for moving the mounting; and a control unit for controlling the drive for moving transport elements and the mounting drive, wherein the control unit is configured: to interrupt the individual-separation mode and stop the transport element drive after the reception of a fault signal, to subsequently activate the mounting drive to move the mounting to increase a distance between the transport elements and the retention element, to subsequently activate the mounting drive to move the mounting to reduce the distance between the transport elements and the retention element, and to shift the apparatus into the individual-separation mode and start the transport element drive.
 2. The apparatus of claim 1, wherein the control unit is configured to carry out the activation of the mounting drive for increasing the distance after expiry of a predetermined increase time span.
 3. The apparatus of claim 1, wherein the control unit is configured to carry out the activation of the mounting drive for increasing the distance after reception of a triggering event.
 4. The apparatus of claim 2, wherein the predetermined increase time span between the activation for increasing the distance and the activation for reducing the distance amounts to at least one and at most three seconds.
 5. The apparatus of claim 1, wherein the control unit is configured: to activate the transport element drive to move at least one transport element for a predetermined movement time span after the activation for decreasing the distance, and to activate reducing the distance at the earliest after expiry of the movement time span.
 6. The apparatus of claim 5, wherein the predetermined movement time span amounts to at least 50 and at most 300 milliseconds.
 7. The apparatus of claim 5, wherein the articles move in the individual-separation mode in a transport direction, and wherein the control unit is configured to activate the transport element drive to cause a movement of the at least one transport element opposite to the transport direction in the movement time span.
 8. The apparatus of claim 1, wherein one of the transport elements and the retention element is arranged such that gravity moves the articles downward in the increase time span.
 9. The apparatus of claim 8, further comprising a conveyer band arranged to transport articles in the increase time span.
 10. The apparatus of claim 1, wherein the mounting is designed as a sliding plate.
 11. The apparatus of claim 1, wherein the control unit is configured: to count how often the control unit has caused activation for increasing the distance, and, if the control unit has carried out activation for increasing the distance a predetermined number of times and a fault signal is present, to renew activation for increasing the distance and renew stopping of the transport element drive, and to shift the apparatus into the individual-separation mode only after reception of a fault elimination signal.
 12. The apparatus of claim 1, wherein the transport elements and the retention element are arranged such that, in the individual-separation mode, they act on the articles non-positively by means of frictional force.
 13. The apparatus of claim 1, further comprising at least one light barrier and an evaluation unit, wherein the evaluation unit is configured: to generate a fault signal when the light barrier is obscured for longer than a predetermined obscuring time span, and to transmit the fault signal to the control unit.
 14. A method of separating flat articles of a stack, comprising: shifting an individual-separation apparatus with a plurality of driven transport elements and at least one retention element into an individual-separation mode; transporting the articles on a transport path through between the transport elements and the retention element to individually separate the articles; automatically transferring the apparatus out of the individual-separation mode into another mode after reception of a fault signal; moving a driven mounting, on which the transport elements or the retention element are fastened, so that a distance between the transport elements and the retention element is increased; moving, after expiry of a predetermined increase time span, the mounting so that the distance between the transport elements and the retention element is reduced; and shifting the apparatus into the individual-separation mode and driving the transport elements.
 15. The method of claim 14, further comprising: after the increase in the distance, moving at least one transport element for a predetermined movement time span, and carrying out the reduction in the distance at the earliest after expiry of the movement time span.
 16. The method of claim 14, further comprising: counting how often the distance has been increased, and, when the increase in the distance has been carried out a predetermined number of times and a fault signal is present, increasing the distance once more, stopping the transport elements, and shifting the apparatus into the individual-separation mode again only when a fault elimination signal is received. 